The need to isolate electronic equipment from ambient environmental conditions is well known. For example, U.S. Pat. No. 4,807,441, issued Feb. 28, 1989 to Keith D. Agree et al. and assigned to Allied-Signal Inc., teaches a cooling system for a sealed enclosure. This enclosure prevents air internal to the cabinet from intermixing with air external to the cabinet. Thus, for example, the equipment cabinet could be placed in an environment of higher humidity than the exposed equipment would tolerate. Heat exchange from the internal air to the external air is accomplished using an externally mounted heat sink or an external corrugated fin arrangement which keeps the internal and external air separated. Both of these arrangements rely on external natural convection for the heat transfer. While this arrangement is adequate for some applications, applications with equipment requiring relatively high power dissipation and with cabinets intended for use outdoors with exposure to various weather conditions, require protection of the heat exchanger fins from exposure to direct solar energy, contamination from dirt, snow, or ice, and corrosion.